An Electromagnetic Wave Has an Electric Field Given By the Wave Number of the Magnetic Field Associated with

Multiple Choice

An electromagnetic wave has an electric field given by $\vec { E } = - \left( 9.0 \times 10 ^ { 5 } \mathrm {~V} / \mathrm { m } \right) \hat { j } \cos \left[ \left( 9.42 \times 10 ^ { 15 } \mathrm { rad } / \mathrm { s } \right) t - k z \right]$ . The wave number of the magnetic field associated with this wave is

A) $3.1 \times 10 ^ { 7 } \mathrm {~m} ^ { - 1 }$
B) $3.0 \times 10 ^ { - 3 } \mathrm {~m} ^ { - 1 }$
C) $3.0 \times 10 ^ { 5 } \mathrm {~m}$
D) $3.1 \times 10 ^ { 7 } \mathrm {~m}$